These studies will concern the genetics and biochemistry of antibiotic resistance in Neisseria gonorrhoeae. The principle tool is genetic transformation. The aim is to genetically characterize a series of mutations responsible for acquisition of resistance to multiple drugs and also other loci which result in phenotypic loss of resistance to all of these drugs. Other studies will concentrate on the biochemical basis for the development of and loss of resistance to multiple drugs. The final phase concerns the isolation and characterization of plasmid DNA from several of the strains by electron microscopy and sedimentation properties.